Note: Descriptions are shown in the official language in which they were submitted.
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LOG SORTER
BACKGROUND
1. Field
This disclosure relates generally to processing of harvested logs and more
specifically to an apparatus,
method and system for sorting logs into diameter ranges.
2. Description of Related Art
Harvested logs from forestry operations are typically transported to a sawmill
by train or truck. Batches of
.. logs arriving at the yard of the sawmill may vary considerably in diameter
and length. The logs in the yard
may be handled by one or more log loaders that use a grapple to pick up
batches of logs and deliver the
logs sawmill equipment for processing. Due to the size of logs and the nature
of the loading equipment it is
not practical to perform any individual sorting and in most cases sawmill
processing must be able to handle
a fairly wide range of different log dimensions. Sawmill processing generally
involves debarking the logs
and then processing the logs through a canter line to cut the logs into cants.
A cant is a piece of wood that
has been sawn on at least three sides. Cants may be further processed into
dimensional lumber. Modern
canter lines are generally highly automated and can adapt their setup for
differences between logs on the
fly. Each log may be passed through a scanner that determines how to best to
orient and cut the log for
optimal yield or utilization. The log is then oriented according to the
scanner determination and passed to
the canter, which is also set up in accordance with the scanner determination.
Since it may be necessary to
frequently change setup between logs, the throughput of logs through a canter
line may be limited. Canter
setup changes takes a finite time and the individual logs in the log feed thus
need to be fed through the
canter line with sufficient spacing between logs to accommodate the setup
change time. This spacing may
in some instances be 10¨ 14 feet.
SUMMARY
In accordance with one disclosed aspect there is provided a log sorting
apparatus. The apparatus includes a
conveyor having a receiving end for receiving a feed of singulated logs, the
conveyor being operable to
transport each log in a lengthwise orientation from the receiving end to one
of a plurality of discharge
locations along the conveyor. Each discharge location includes a longitudinal
conveyor section and is
associated with a range of log diameters. The apparatus also includes a log
diameter sensor disposed
proximate the receiving end of the conveyor and operable to determine a log
diameter for each log
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received at the receiving end of the conveyor. The apparatus further includes
a plurality of actuators, each
actuator associated with at least one discharge location and selectively
actuable by a controller to laterally
discharge logs from the longitudinal conveyor section that fall within the
range of diameters associated
with the discharge location. Each actuator includes at least one arm that
exerts a lateral force on the log
when actuated by the controller to cause the lateral discharge of the log at
the discharge location.
Each actuator may include at least one arm that exerts a lateral force on the
log when actuated by the
controller to cause the lateral discharge of the log at the discharge
location.
Each actuator may further include a hydraulic cylinder coupled to the at least
one arm.
Each conveyor section may be associated with a first discharge location to a
first lateral side of the
conveyor section and a second discharge location to a second lateral side of
the conveyor section and each
respective actuator may be selectively operable to discharge logs in a first
diameter range to the first lateral
side of the conveyor section and to discharge logs in a second diameter range
to the second lateral side of
the conveyor section.
Each actuator may include a first arm disposed to engage a side of the log
opposite to the first lateral side
when actuated and a second arm disposed to engage a side of the log opposite
to the second lateral side
when actuated and the first arm and second arm may be disposed to permit the
log to pass between the
first and second arms when not actuated.
The actuator may include a horseshoe shaped body having the first arm and
second arm disposed on open
ends of the horseshoe shaped body.
The apparatus may include a frame disposed at each discharge location, the
frame being operable to
receive and accumulate logs discharged from the conveyor at the discharge
location.
The frame may include a plurality of pairs of crossed beams, each pair of
crossed beans being spaced apart
from an adjacent pair of crossed beams along the longitudinal conveyor section
and forming a bunk for
receiving discharged logs.
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The crossed beams may be spaced to permit access of a grapple of a loader to
simultaneously grasp a
plurality of logs accumulated in the bunk.
Each log may be spaced apart from other logs in the feed of singulated logs by
a spacing distance and may
further include at least one proximity sensor disposed at each discharge
location along the conveyor, the
proximity sensor being operable to generate a proximity signal for tracking
movement of each log along the
conveyor, and the controller may be operably configured to receive the
proximity signal and cause the
actuator to discharge each log at one of the discharge locations having an
associated log diameter range
corresponding to the determined diameter of the log.
The apparatus may include a feeder disposed at the receiving end of the
conveyor and operably configured
to receive pluralities of logs from a loader and to singulate the logs to
provide the feed of singulated logs at
the receiving end of the conveyor.
.. The feeder may include a log deck and a step feeder, the log deck being
operably configured to receive the
pluralities of logs from the loader and transport the logs to the step feeder,
the step feeder being operably
configured to separate and deliver singulated logs to the receiving end of the
conveyor.
The conveyor may include a mill chain extending between a first sprocket
disposed at the receiving end of
.. the conveyor and a second sprocket disposed at an end of the plurality of
longitudinal conveyor sections, at
least one of the first and second sprockets being driven by a motor to cause
the mill chain to be advanced
to transport the logs along the conveyor.
The mill chain may include a plurality of v-blocks mounted on and spaced apart
along on the mill chain and
having an angle selected to receive and support each singulated log at the
receiving end for transport along
the conveyor while facilitating lateral discharge of the logs at the
respective discharge locations.
The log diameter sensor may include a light curtain operably configured to
optically measure the diameter
of each log transported past the sensor.
In another disclosed aspect a system for processing harvested logs into lumber
is disclosed. The system
may include the log sorting apparatus above that is operable to sort logs into
pluralities of sorted logs
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having a diameter within a range of diameters. The system also includes at
least one debarking apparatus,
configured to remove bark from each sorted plurality of logs loaded at one of
the discharge locations. The
apparatus further includes at least on canter line operable to receive one of
the sorted pluralities of
debarked logs and to cut the logs into cants, the at least one canter line
having been previously configured
to process logs within one of the diameter ranges.
A spacing between successive logs in the sorted plurality of debarked logs on
the canter line may be less
than about 18 inches.
.. In accordance with another disclosed aspect there is provided a method for
sorting logs for processing in a
sawmill. The method involves receiving a feed of singulated logs at a
receiving end of a conveyor, the
conveyor being operable to transport each singulated log in a lengthwise
orientation from the receiving end
along the conveyor. The method also involves determining a diameter of each
singulated log received at
the receiving end of the conveyor, and causing each log to be discharged from
the conveyor at one of the
plurality of locations along the conveyor, each location being associated with
a range of diameters. Causing
each log to be discharged involves causing at least one arm to exert a lateral
force on the log to cause the
lateral discharge of the log at the discharge location.
In accordance with another disclosed aspect there is provided a method for
processing harvested logs into
lumber. The process involves sorting the logs in accordance with the method
above into pluralities of
sorted logs having a diameter within a range of diameters. The method further
involves debarking each
sorted plurality of logs loaded at one of the discharge locations. The method
also involves receiving one of
the sorted pluralities of debarked logs on a canter line operable to cut the
logs into lumber, the at least one
canter line having been previously configured to process logs within one of
the diameter ranges.
In accordance with another disclosed aspect there is provided a log sorting
apparatus. The apparatus
includes a conveyor having a receiving end for receiving a feed of singulated
logs, the conveyor being
operable to support and transport each log in a lengthwise orientation from
the receiving end to one of a
plurality of discharge locations along the conveyor. Each discharge location
includes a longitudinal
.. conveyor section and being associated with a range of log diameters, a log
diameter sensor disposed
proximate the receiving end of the conveyor and operable to determine a log
diameter for each log
received at the receiving end of the conveyor, and a plurality of actuators,
each actuator associated with at
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least one discharge location and selectively actuable by a controller to
laterally discharge logs from the
longitudinal conveyor section that fall within the range of diameters
associated with the discharge location.
Each of the plurality of actuators includes a horseshoe shaped body pivotably
mounted below the conveyor
and having a first arm and second arm disposed on open ends of the horseshoe
shaped body, the first and
second arms extending around the conveyor such that respective the arms are
disposed to exert a lateral
force on the log when actuated by the controller to cause the lateral
discharge of the log at the discharge
location.
Other aspects and features will become apparent to those ordinarily skilled in
the art upon review of the
following description of specific disclosed embodiments in conjunction with
the accompanying figures.
BRIEF DESCRIPTION OF THE DRAWINGS
In drawings which illustrate disclosed embodiments,
Figure 1 is a plan view of a log sorting apparatus in accordance with a
first disclosed embodiment;
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Figure 2 is a perspective view of one of a plurality of supports
making up a conveyor of the log sorting
apparatus shown in Figure 1;
Figure 3 is a perspective view of a plurality of the supports
shown in Figure 2 configured to provide two
successive longitudinal conveyor sections;
Figure 4 is a schematic view of a control system for controlling
the log sorting apparatus shown in
Figure 1;
Figure 5 is a process flowchart showing block of codes for directing a
microprocessor based controller
of the control system shown in Figure 4 to control operation of the log
sorting apparatus;
Figure 6 is a table representing values stored in a memory of the
controller while implementing the
process shown in Figure 5;
Figure 7 is a table showing possible ranges of diameter
associated with each of a plurality of discharge
locations implemented by the log sorting apparatus; and
Figure 8 is a block diagram of a system for processing harvested
logs into lumber.
DETAILED DESCRIPTION
Referring to Figure 1, a log sorting apparatus in accordance with a disclosed
embodiment is shown in plan
view generally at 100. The log sorting apparatus 100 may be located at a
sawmill for processing harvested
logs. The log sorting apparatus 100 includes a conveyor 102 having a receiving
end 104 for receiving a feed
of singulated logs, where a singulated log (such as the log shown at 106) is a
log that has been separated
from other logs. The conveyor 102 is operable to transport each log in a
lengthwise orientation (i.e. in the
direction of arrow 108) from the receiving end 104 to one of a plurality of
discharge locations 110 ¨ 116
along the conveyor. In the embodiment shown the conveyor 102 is implemented
using an endless mill
chain 150 having a plurality of links 152 and log supports 154 attached to the
links for supporting the logs
for transport along the conveyor 102. The mill chain 150 extends around a
first sprocket 156 at the
receiving end 104 and a second sprocket 158 located at a distal end of the
conveyor 102 and is driven by an
electric motor 160 at the second sprocket to cause the mill chain to advance
to transport logs along the
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conveyor 102. In this embodiment the log supports 154 are configured as v-
blocks mounted on and spaced
apart along on the mill chain 150. The singulated logs may be rolled onto the
v-blocks at the receiving end
104 of the conveyor 102. The v-blocks have support faces at an angle selected
to retain the log in the
support 154. Each singulated log would thus be received and supported by a
plurality of the v-block log
supports 154 at the receiving end 102 for travel along the conveyor while also
facilitating lateral discharge
of at the respective discharge locations 110 - 116.
Each of the discharge locations 110 ¨ 116 extends along a longitudinal
conveyor section. In the
embodiment shown in Figure 1 the discharge locations 110 and 112 share a
longitudinal conveyor section
118 and the discharge locations 114 and 116 share a longitudinal conveyor
section 120. The discharge
locations 110 and 114 are to a first lateral side of the conveyor sections 118
and 120 while the discharge
locations 112 and 116 are to a second lateral side of the conveyor sections.
In other embodiments only a
single discharge location may be associated with each longitudinal conveyor
section.
The log sorting apparatus 100 also includes a log diameter sensor 122 disposed
proximate the receiving end
104 of the conveyor 102. The log diameter sensor 122 is operable to determine
a log diameter for each log
received at the receiving end 104 of the conveyor. In the embodiment shown a
log 124 is currently passing
over the sensor 122, which scans and determines a diameter of the log. In one
embodiment the sensor 122
may be a ScanMeg Type HD light curtain scanner available from ScanMeg of
Boisbriand, Quebec Canada.
The ScanMeg light curtain scanner is able to measure a wide range of log
diameters to an accuracy of about
1 mm using infrared light beams. In other embodiments the log diameter sensor
may be implemented
using a sensor based on other optical or non-optical measuring technology.
The log sorting apparatus 100 further includes a plurality of actuators
selectively actuable to laterally
discharge logs from the longitudinal conveyor section that fall within the
range of diameters associated
with the discharge location. In the embodiment shown, a plurality of actuators
126 are disposed along the
longitudinal conveyor section 118, in this case associated with both the
discharge location 110 and the
discharge location 112.
In the embodiment shown in Figure 1 the longitudinal conveyor section 118 is
made up of four similar
supports 130, 132, 134, and 136, which support the conveyor 102 and the
actuators 126. Referring to
Figure 2, the support 130 is shown in perspective view. The support 130
includes a concrete base 200,
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which rests on the ground and to which a pair of upright beams 202 are
mounted. The support 130 also
includes a cross plate 204 attached to upper ends of the upright beams 202. In
this embodiment, the
actuator 126 is implemented as a horseshoe shaped kicker 206 having a first
arm 208 and a second arm 210
disposed on open ends of a horseshoe shaped body. The kicker 206 is pivotably
mounted on a shaft 212
extending outwardly from the cross plate 204 and is able to pivot in either
direction, as indicated by the
arrow 214, thus causing the arms to move in a generally lateral direction with
respect to the conveyor 102.
The kicker 206 is actuated by a hydraulic cylinder 216, which receives a flow
of hydraulic fluid from a
hydraulic system (shown in Figure 4) causing a piston rod 218 to extend or
retract to cause the kicker 206 to
rotate anticlockwise to the right or clockwise to the left. The arms 208 and
210 are disposed to exert a
generally lateral force on a log when the kicker 206 is rotated, thus causing
lateral discharge of the log.
Following discharge of the log, the hydraulic cylinder 216 is operated to
return kicker 206 to an unactuated
or centrally oriented position, which permits logs to pass between the first
and second arms 108 and 210.
In this embodiment the support 130 further includes pair of beams 220, 222 and
224, 226 mounted in a
crossed or "X" configuration on each lateral side of the support. The crossed
beams 220, 222, 224 and 226
of the support 130 together with spaced apart beams of adjacent supports 132,
134 and 136 form a frame
or bunk for receiving laterally discharged logs from the conveyor section 118.
In the embodiment shown
there are four laterally disposed bunks 140, 142, 144, and 146 (labeled in
Figure 1 as bunks 1A, 1B, 2A and
2B respectively). The crossed beams of each bunk 140 ¨ 146 are spaced apart to
permit access for a
grapple of a loader to simultaneously grasp a sorted plurality of logs
accumulated in the bunk. Each bunk
140 ¨ 146 accumulates logs discharged at the respective discharge locations
110 ¨ 116. Logs accumulated
in the bunks 140 ¨ 146 may be conveniently loaded by a logging grapple of a
log loader for further
processing as a sorted plurality of logs, which will have diameters that fall
within the range associated with
the discharge location.
Still referring to Figure 2, the mill chain 150 of the conveyor 102 (a portion
of which is shown in Figure 2)
passes through a central opening in the horseshow shaped kicker 206 between
the pair of arms 208 and
210. The support 130 further includes upper and lower chain supports 230 and
232, each configured as a
U-channel beam extending along the conveyor 102 between adjacent supports. The
upper chain support
230 is attached to the cross plates 204 and the lower chain support 232 is
attached between the pair of
upright beams 202 below the kicker 206.
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In the embodiment shown in Figure 1 the longitudinal conveyor section 118
includes four supports 130,
132, 134, and 136 and the longitudinal conveyor section 120 also includes four
similar supports. The
longitudinal conveyor sections 118 and 120 are shown in perspective view in
Figure 3 with the mill chain
150 being omitted in the Figure for sake of clarity. Referring to Figure 4,
each of the supports 130 ¨ 136 are
configured as shown in Figure 2, except that the support 136 has the kicker
206 mounted behind the cross
plate 204. The kickers 206 of each of the supports 130 ¨ 136 may also not be
regularly spaced along the
conveyor 102. For example the kicker 206 of the support 130 may be spaced
about 5 feet from the kicker
of the support 132, which is spaced about 4 feet from the kicker of the
support 134. The kicker of the
support 136 is spaced apart from the kicker of the support 134 by about 5
feet. The longitudinal conveyor
sections 118 and 120 are similarly configured for discharging logs of
different length, in one embodiment
between about 8 feet and 20 feet in length.
In the embodiment shown in Figure 1, the log sorting apparatus 100 includes a
feeder 168 for providing a
feed of singulated logs to the receiving end 104 of the conveyor 102. In the
embodiment shown the feeder
168 includes a log deck 170 and a step feeder 172. The log deck 170 is
operably configured to receive
batches of logs from a log loader (not shown) and includes a conveyor 174
driven by a motor 176 that
transports the logs to the step feeder 172. The step feeder 172 has a
mechanism that separates the logs
and conveys individual logs to the receiving end 104 of the conveyor 102. In
one embodiment the step
feeder 172 may be implemented using a double acting step feeder available from
Linden Fabricating Ltd. of
Prince George, BC, Canada. In one embodiment the conveyor 102 runs at a
conveyor speed of about 450
feet per minute.
While only two longitudinal conveyor sections 118 and 120 are shown in Figure
1 and Figure 3, in practice
additional longitudinal conveyor sections may be implemented to provide any
desired number of discharge
locations and bunks. For example, in one embodiment 5 longitudinal sections of
conveyor may be arranged
end-to-end to implement a log sorting apparatus having ten bunks. The number
of bunks may be selected
in accordance with a range of harvested log diameters typically received at
the sawmill and also based on
the canter lines available at the sawmill for processing logs.
Referring back to Figure 1, the log sorting apparatus 100 also includes a
proximity sensor 164 disposed at
the discharge location 110, 112 along the conveyor 102. The proximity sensor
generates a proximity signal
for tracking movement of the logs along the conveyor. The proximity sensor 164
generates proximity
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signals indicating whether or not a log is proximate the sensor. In one
embodiment the feeder 168 is
configured to cause each log in the feed of singulated logs traveling along
the conveyor 102 to be relatively
closely spaced, typically by a spacing distance of about 12 inches and no more
than 18 inches. The signal
generated by the proximity sensor 164 will thus having either a first state
indicating that a log is in front of
the sensor or a second state indicating that a space between logs is in front
of the proximity sensor. A
further proximity sensor 166 is disposed at the beginning of the conveyor
section 120 ahead of the
discharge locations 114, 116. In one embodiment the proximity sensor 164 and
the proximity sensor 166
may be implemented using a Q4X photoelectric proximity sensor available from
Banner Engineering Corp.,
Minneapolis, MN, USA.
A control system for controlling the log sorting apparatus 100 is shown in
Figure 4 at 400. The control
system 400 includes a controller 402 having an interface 404 for receiving log
diameter signals from the log
diameter sensor 122, and an interface 406 for receiving proximity signals from
proximity sensors 164 and
166. In one embodiment the controller 402 may be implemented using a
microprocessor based controller
.. circuit, which would generally include a microprocessor and memory such as
RAM memory for storing data
during operation and/or a flash memory for storing program codes for
configuring the controller to perform
control functions.
The control system 400 also includes a hydraulic valve 410, a hydraulic fluid
pump 412, and a hydraulic fluid
reservoir 414. The controller 402 also includes an interface 408 for producing
control signals for controlling
operation of the hydraulic pump 412 and the valve 410 via a solenoid 416. The
valve 410 is responsive to
electrical signals received from the interface 408 at the solenoid 416 to
switch between three valve states.
In a first state illustrated by the central valve symbol 418, when the
hydraulic pump 412 is actuated by the
control signal received from the interface 408, hydraulic fluid is drawn from
the reservoir 414 via a line 420
and returned to the reservoir via a line 422. No fluid is delivered to the
hydraulic cylinder 216.
In a second state illustrated by the right hand valve symbol 424, the
hydraulic fluid drawn from the
reservoir 414 is passed through the valve 410 to a first port 430 of the
hydraulic cylinder 216. At the same
.. time, hydraulic fluid is discharged through a second port 432 of the
hydraulic cylinder 216 and returned via
the valve 410 to the reservoir 414. Under these conditions the piston rod 218
of the hydraulic cylinder 216
extends causing the kicker 206 to rotate anticlockwise about the shaft 212.
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In a third state illustrated by the left hand valve symbol 426, the hydraulic
fluid drawn from the reservoir
414 is passed through the valve 410 to a second port 432 of the hydraulic
cylinder 216. At the same time,
hydraulic fluid is discharged through the first port 430 of the hydraulic
cylinder 216 and returned via the
valve 410 to the reservoir 414. Under these conditions the piston rod 218 of
the hydraulic cylinder 216
retracts causing the kicker 206 to rotate clockwise about the shaft 212.
In one embodiment each of the supports 130 ¨ 136 associated with the conveyor
sections 118 may be
connected to the same valve 410 and controlled by the control system 400 to
operate the respective
hydraulic cylinders 216 together. In other embodiments each support 130 ¨ 136
may have its own valve
410 to permit individual control of the kickers associated with the supports.
This would have the advantage
of only actuating kickers that were necessary to discharge the log at one of
the discharge locations 110 ¨
116 based on the length of the log. The length of the log may be determined
either at the log diameter
sensor 122 or by the proximity sensors 164 and 166, based on the conveyor
speed.
In one embodiment the controller 402 and interfaces 404, 406, and 408 may be
implemented using a
microprocessor based programmable logic controller (PLC), such as the Allen-
Bradley ControlLogix 5580
Controller available from Rockwell Automation Inc. of Wisconsin, U.S.A. The
Allen-Bradley ControlLogix
5580 PLC may be combined with various interface modules to provide the
required functionality for
monitoring the sensors and controlling the hydraulics as shown in Figure 4.
The interfaces 404, 406, and
408 may be implemented using off-the-shelf interface modules suitable for
interfacing with the respective
log diameter sensor 122, the proximity sensor 164, the proximity sensor 166,
valve 410, and hydraulic
pump 412. The signals from the sensors may be received at the interface as
digital signals (for example RS
¨ 522 serial signals or other signal formats) or analog signals (for example,
4-20 mA output signals or other
signal formats).
Referring to Figure 5, a flowchart depicting blocks of code for directing a
microprocessor based controller
402 to control the log sorting apparatus 100 is shown generally at 500. The
blocks generally represent
program codes that may be read from a computer readable medium such as a flash
memory device for
directing the microprocessor to perform various functions related to log
sorting. The actual code to
implement each block may be written in any suitable programming program
language, such as Ladder
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Diagram, Structured Text), Function Block Diagram, Instruction List,
Sequential Flow Chart, used for PLC
programming or any other programing language.
The process begins at 502, where the controller 402 is initialized. Block 502
may direct the microprocessor
to load the program codes, perform internal checks, and establish
communication with the sensors 122,
164, 166, the hydraulic pump 412, and valve 410. Block 502 also directs the
microprocessor to produce
signals at the interface 408 for activating the hydraulic pump 412 and to
place the valve 410 in the first
state 418, where no fluid is being delivered to the hydraulic cylinder 216.
Under these conditions the kicker
206 would remain centered as shown in Figure 2 and logs are free to pass
between the pair of arms 208
and 210 along the conveyor 102. Block 504 then directs the microprocessor to
initiate three process
threads 504, 506, and 508, which are described below and run in parallel
during operation of the log sorting
apparatus 100.
The process thread 504 directs the microprocessor of the controller 402 to
receive and record log
diameters and starts at block 510. Block 510 directs the microprocessor to
receive signals from the log
diameter sensor 122 at the interface 404, and based on the received signals to
determine whether a log is
passing over the diameter sensor. In one embodiment the step feeder 172 causes
singulated logs to be
spaced apart by about 12 ¨ 18 inches. When a log (such as the log 124 in
Figure 1) passes from the
receiving end 104 of the conveyor over the diameter sensor 122, the sensor
will detect the presence of the
log begin producing an output signal representing the diameter of the log.
When no log is located over the
log diameter sensor 122 the output of the sensor log diameter sensor 122 will
produce a signal indicating
that there is a gap between singulated logs (i.e. a no-diameter state). If at
block 510 it is determined that
no log is detected at the log diameter sensor 122 then the microprocessor is
directed to repeat block 510.
If at block 510 it is determined that a log diameter is being detected at the
diameter sensor 122 then the
microprocessor is directed to block 512.
Block 512 directs the microprocessor to receive the diameter signal and
extract a diameter value provided
by the log diameter sensor 122. Block 514 then directs the microprocessor to
again determine whether the
signal currently being received from the log diameter sensor 122 indicates
that there is still a log above the
sensor, in which case the microprocessor is directed back to block 512 to read
and average the received log
diameter. If at block 514 the signal produced by the log diameter sensor 122
has a no-diameter state then
the log has been transported away from the sensor 122 indicating the presence
of a gap between
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singulated logs. By detecting the spaces between logs (provided through
operation of the step feeder) the
controller 402 is able to assign individual diameters to each singulated log
in the feed. Block 514 then
directs the microprocessor to block 516 where the average log diameter is
recorded in the memory of the
controller 402. In one embodiment a sequence number may also be assigned to
each singulated log and
the average log diameter may be recorded along with the log sequence number in
a memory of the
controller 402. An example of diameter values stored in memory is shown in
Figure 6 represented by a
table 600, where the log 124 has been assigned a sequence number of 1 and a
diameter of 18.5 inches.
Block 516 then directs the microprocessor to block 518, where the sequence
number is incremented and
the microprocessor directed back to block 510 to await the next singulated
log. As shown in Figure 6, the
process thread 504 results in the memory table 600 being populated with a
sequence of averaged log
diameters for each of the singulated logs 124 and 106 and for subsequent
singulated logs in the feed.
The process thread 506 that runs in parallel with the process thread 504
starts at block 520. Block 520
directs the microprocessor to receive the proximity signal from the proximity
sensor 164 and to determine
whether a log is being detected at the proximity sensor 164. As shown in
Figure 1, the proximity sensor 164
is located at a point along the conveyor 102 ahead of the longitudinal
conveyor section 118. When the
signal received from the proximity sensor 164 indicates that no log is
currently being transported past the
sensor, block 520 directs the microprocessor to repeat the block. When at
block 520 the sensor indicates
that a log has been detected at the sensor, the microprocessor is directed to
block 522. Block 522 directs
the microprocessor to determine whether the log has been transported past the
proximity sensor 164.
When the signal produced by the proximity sensor 164 changes to indicate that
no objects are detected
within the range of the sensor, a gap between the logs is currently passing
the sensor. Accordingly, when at
block 522 a log is still detected, the microprocessor is directed back to
block 522. When at block 522 a log
is no longer detected, the microprocessor is directed to block 524. Once the
log passes the proximity
sensor 164 the log will generally extend along the longitudinal conveyor
section 118.
Block 524 directs the microprocessor to determine whether the log diameter of
the log currently disposed
on the longitudinal conveyor section 118 matches the diameter range of the
Bunk A (140). Referring to
Figure 7, as an example, the bunks 140 ¨ 146 may be assigned log diameter
ranges as set out in the table
700. Smaller diameter logs in this embodiment are discharged to the right to
bunks 1B (logs less than
8 inches in diameter) and 2B (logs more than 8 inches but less than 13 inches
in diameter). Larger diameter
logs are discharged to the left to bunks 1A (logs greater than 18 inches in
diameter) and 2A (logs more than
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13 inches but less than 18 inches in diameter). Other log ranges may be
established depending on the
nature of logs being processed and the further processing requirements of the
sawmill.
Block 524 then directs the microprocessor to read the next log in sequence in
the memory table 600 shown
in Figure 6. In the example shown, the next singulated log is the log 124
having an assigned sequence of
"1" and a measured average diameter of "18.5", which falls within the bunk 1A
diameter range. Block 524
thus directs the microprocessor to block 526. Block 526 directs the
microprocessor to cause signals to be
produced at the interface 408 to place the valve 410 in the second state 424
resulting in the hydraulic
cylinder 216 being extended and the kicker 206 rotated anticlockwise about the
shaft 212 such that the arm
210 engages the log 224. Referring back to Figure 3, the log 124 is shown at
the conveyor section 118 and
the hydraulic cylinders 216 have been extended at each of the supports 130 ¨
136 to cause the kickers 206
to rotate anticlockwise about the shaft 212. The rotation of the kickers 206
causes the respective arms 210
to engage and discharge the log laterally into the bunk 1A (140). The
plurality of actuators 126 ensures that
the log is discharged in an orientation generally parallel to the conveyor
102. A log 302, also falling within
the diameter range for bunk 1A, has been previously discharged at the
discharge location 110 and is
supported within the beams 220 and 222 of the bunk.
Block 532 then directs the microprocessor to cause the valve 410 to be placed
in the third state 426
retracting the piston rod 218 of the hydraulic cylinder 216 and returning the
kicker 206 to the central
orientation. The process 506 then continues at block 534, which directs the
microprocessor to flag the log
as having been discharged from the longitudinal conveyor section 118 of the
conveyor 102. In one
embodiment the entry for the log 124 in the memory table 600 (Figure 6) may be
deleted from memory,
indicating that the log has been discharged. In other embodiments, the entry
for the log 124 may include
an additional flag (not shown) indicating that the log has been discharged.
Block 534 then directs the
microprocessor back to block 520 and the process 506 is repeated for the next
log in the log feed.
If at block 524 the log does not fall within the diameter range of bunk 1A,
the microprocessor is directed to
block 528. Block 528 directs the microprocessor to determine whether the log
falls within the diameter
range of bunk 1B. If the log also does not fall within the diameter range of
bunk 1B, block 528 directs the
microprocessor back to block 520. In this case the kickers 206 of the conveyor
section 118 remain centered
and the log is transported through the conveyor section to the next conveyor
section 120. If at block 528,
the log falls within the diameter range of bunk 1B, the microprocessor is
directed to block 530. Block 530
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directs the microprocessor to cause signals to be produced at the interface
408 to place the valve 410 in the
third state 426. This would result in the hydraulic cylinder 216 being
retracted and the kicker 206 rotated
clockwise about the shaft 212 such that the arm 208 engages the log 224. The
microprocessor is then
directed to blocks 532 and 534, which as described above return the kicker 206
to a central orientation and
flag the log as having been discharged.
The control system 400 also implements the process thread 508, which is
identical to the process 506 but
operates on the second proximity sensor 166 and for the conveyor section 120.
When determining
whether the log is within the diameter range of the bunks at blocks 536 and
540, the diameter of the log
having the lowest sequence number in the memory table 600 is read. Since any
discharged logs will have
been flagged as such, the log at the longitudinal conveyor section 120 should
be the log in the memory
table 600 having the lowest sequence number. Additional logic may be necessary
to resolve possible
conflicts in the event that a log diameter is read from the memory table 600
by either of blocks 524 and 526
at the same instant as a log diameter is being read from the memory table 600
by either of blocks 536 and
540.
In embodiments having additional longitudinal conveyor sections, the process
thread 406 would be
implemented for each additional section to cause logs that fall within the
diameter range associated with
each section to be discharged laterally to either the left or right at the
applicable discharge locations.
The embodiments of the log sorting apparatus 100 disclosed above thus provide
a sorting apparatus that
may be easily configured to suit the range of logs being received at a
sawmill.
A system for processing harvested logs into lumber incorporating the log
sorting apparatus 100 shown in
Figures 1 ¨ 4 is shown in Figure 8 at 800. Referring to Figure 8, the system
800 includes the log sorting
apparatus 100 and controller 402 as described above that operates to sort logs
into pluralities of sorted
logs having a diameter within a range of diameters. In the embodiment shown
the system further includes
a first debarking apparatus 802 and a second debarking apparatus 802 which
operate to remove bark from
the sorted pluralities of logs. In one embodiment a log loader will load logs
from one of the bunks 140 ¨
146 and transport the logs to one of the debarkers 802 or 804. Having more
than one debarker provides
some redundancy in the event of a failure and also provides additional
capacity for debarking.
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The system 800 also includes a canter line 806. The canter line receives
debarked and cuts the logs into
lumber. Modern canter lines are generally highly automated and can be set up
to handle logs having quite
substantial differences in diameter by reconfiguring saw blades to obtain a
desirable lumber yield from
each log. In one embodiment the controller 402 may communicate sorted diameter
range date to the
canter line to permit configuration prior to the logs being received from
processing into lumber. One
advantage of the system 800 in including the log sorting apparatus 100 is that
sorted pluralities of logs
within one of the diameter ranges may be fed through the canter line 806 in
batches. This facilitates setup
of the canter line for optimal utilization of the logs and also permits the
logs to be fed to the canter line 806
with minimal spacing between logs (typically less than about 18 inches). In
some prior systems where logs
are fed to the canter line 806 unsorted, the line must sense the diameter of
each log and configure for
optimal utilization. This places a practical limitation on the spacing between
logs, in many cases requiring
that the feed of logs have a separation of many feet, and typically about 14
feet depending on the
capability of the canter line automated setup process.
The disclosed embodiments provide a log sorting apparatus that improves the
overall efficiency of
operating a sawmill system such as shown in Figure 8 and also facilitates
increased productivity of the
canter line 806. The canter line 806 is usually associated with a high capital
cost and complex setting
procedures. In contrast the log sorting apparatus 100 would involve a
significantly lower capital cost and
has comparatively low complexity and simpler maintenance when compared to the
canter line. The
disclosed log sorting apparatus 100 thus has the potential for significantly
improving operating efficiency of
the sawmill system.
While specific embodiments have been described and illustrated, such
embodiments should be considered
illustrative only and not as limiting the disclosed embodiments as construed
in accordance with the
accompanying claims.
CA 3011308 2018-07-11
